Visualizing nanoscale electronic band alignment at the La$_{2/3}$Ca$_{1/3}$MnO$_{3}$/Nb:SrTiO$_{3}$ interface

Cross-sectional scanning tunnelling microscopy and spectroscopy (XSTM/S) were used to map out the band alignment across the complex oxide interface of La$_{2/3}$Ca$_{1/3}$MnO$_{3}$/Nb-doped SrTiO$_{3}$. By a controlled cross-sectional fracturing procedure, unit-cell high steps persist near the interface between the thin film and the substrate in the non-cleavable perovskite materials. The abrupt changes of the mechanical and electronic properties were visualized directly by XSTM/S. Using changes in the DOS as probe by STM, the electronic band alignment across the heterointerface was mapped out providing a new approach to directly measure the electronic properties at complex oxide interfaces.